46 ACOTYLEDONS. LICHENS. J'arwlaria. 



greyish, warts of the apothecia convex half imrqersed whiter, 

 orifices much contracted radiated with fissures concealing the 

 flesh-coloured apothecia. Acli. Syn. Lick. p. 116. Lichen 

 exanthematicus, p. 1184. 



HAB. Calcareous rocks, Dickson. 



Of this very pretty little Lichen, Acharius observes, that it has a habit 

 peculiar to itself; but that it corresponds better with this genus 

 than with any other. 



13. PYRENULA. 



Universal receptacle crustaceous, spreading, plane, adnate, uni- 

 form ; with wart-like processes including or surrounding at the 

 base a solitary, simple, thick (black), papillary partial re- 

 ceptacle, which contains a globose cellular nucleus. 



1. P. ?iigrescens, crust tartareous somewhat tessellated unequal 

 brownish black, warts of the apothecia spreading at the base 

 depressed somewhat rugose surrounding the greater part of the 

 prominent apothecia. Ach. Syn. Lich. p. \ZQ. Perrucaria 

 umbrina, E. B. I. 1499. 



HAB. Rocks, not uncommon, Mr. Turner and Flook. 



14. VARIOLARIA. 



Unwersal receptacle crustaceous, expanded, plane, adnate, uni- 

 form. Partial receptacle waited, formed of the thallus (ge- 

 nerally sorediform), somewhat margined (white). Nucleus 

 compressed, cellular, concealed within the substance of the warts. 



1 . V. amara, crust rugose cracked uneven subptilverulent white 

 or greyish, warts of the apothecia appressed plano-concave 

 margined bearing soredia of the same colour as the crust. 

 Adi. Syn. Licfi. p. 131. Lichen fagineus, Lightf. p. 807. 

 E.B.-t.\7\3. 



/3. discoidea, crust pulverulent white at length greyish naked, 

 soredia crowded at length spreading waved plano-concave with 

 the margin raised swollen. Lichen discoideus, E. B. t. 1714. 

 L. carpineus, Lightf. p. 807. 



HAB. a. On the bark of beech, oak, and other trees, frequent. /3. On 

 the smooth bark of beech and other trees, Lightf., Hopk. 



Var. a. is highly bitter. Mr. Turner observes, that the bitter flavour 

 is not found in /3. 



2. V. laclca, crust tartareous distinctly bordered cracked smooth 

 white the circumference somewhat zoned crenato-lobate, warts 

 of the apothecia crowded margined very white and pulverulent. 

 Ach. Syn. Lich. p. 132. .E. B. t. 2410. 



HAB. On rocks, common. Whin stones, on Campsie and Cathkin 

 hills, Hopk. 



